Answer: 1687.5 N
Explanation:
From the second law of motion given by Newton, Force is the rate change of momentum.
![F = \frac{dp}{dt}=\frac {m dv}{dt} = \frac{m (v_f-v_i)}{dt}](https://tex.z-dn.net/?f=F%20%3D%20%5Cfrac%7Bdp%7D%7Bdt%7D%3D%5Cfrac%20%7Bm%20dv%7D%7Bdt%7D%20%3D%20%5Cfrac%7Bm%20%28v_f-v_i%29%7D%7Bdt%7D)
Mass of the baseball, m = 0.15 kg
Initial velocity,
(negative because direction of initial velocity is opposite to the final velocity)
Final velocity, ![v_f=50 m/s](https://tex.z-dn.net/?f=v_f%3D50%20m%2Fs)
The duration of collision, ![dt= 8.0 \times 10^{-3} s](https://tex.z-dn.net/?f=dt%3D%208.0%20%5Ctimes%2010%5E%7B-3%7D%20s)
Force, ![F = \frac{0.15 kg (50-(-40) m/s)}{8.0 \times 10^{-3} s}=1687.5 N](https://tex.z-dn.net/?f=%20F%20%3D%20%5Cfrac%7B0.15%20kg%20%2850-%28-40%29%20m%2Fs%29%7D%7B8.0%20%5Ctimes%2010%5E%7B-3%7D%20s%7D%3D1687.5%20N)
Hence, the value of force is 1687.5 N.
The speed of the brick dropped by the builder as it hits the ground is 17.32m/s.
Given the data in the question;
Since the brick was initially at rest before it was dropped,
- Initial Velocity;
![u = 0](https://tex.z-dn.net/?f=u%20%3D%200)
- Height from which it has dropped;
![h = 15m](https://tex.z-dn.net/?f=h%20%3D%2015m)
- Gravitational field strength;
![g = 10N/kg = 10 \frac{kg.m/s^2}{kg} = 10m/s^2](https://tex.z-dn.net/?f=g%20%3D%2010N%2Fkg%20%3D%2010%20%5Cfrac%7Bkg.m%2Fs%5E2%7D%7Bkg%7D%20%3D%2010m%2Fs%5E2)
Final speed of brick as it hits the ground; ![v = \ ?](https://tex.z-dn.net/?f=v%20%3D%20%20%5C%20%3F)
<h3>Velocity</h3>
velocity is simply the same as the speed at which a particle or object moves. It is the rate of change of position of an object or particle with respect to time. As expressed in the Third Equation of Motion:
![v^2 = u^2 + 2gh](https://tex.z-dn.net/?f=v%5E2%20%3D%20u%5E2%20%2B%202gh)
Where v is final velocity, u is initial velocity, h is its height or distance from ground and g is gravitational field strength.
To determine the speed of the brick as it hits the ground, we substitute our giving values into the expression above.
![v^2 = u^2 + 2gh\\\\v^2 = 0 + ( 2\ *\ 10m/s^2\ *\ 15m)\\\\v^2 = 300m^2/s^2\\\\v = \sqrt{300m^2/s^2}\\ \\v = 17.32m/s](https://tex.z-dn.net/?f=v%5E2%20%3D%20u%5E2%20%2B%202gh%5C%5C%5C%5Cv%5E2%20%3D%200%20%2B%20%28%202%5C%20%2A%5C%2010m%2Fs%5E2%5C%20%2A%5C%2015m%29%5C%5C%5C%5Cv%5E2%20%3D%20300m%5E2%2Fs%5E2%5C%5C%5C%5Cv%20%3D%20%5Csqrt%7B300m%5E2%2Fs%5E2%7D%5C%5C%20%5C%5Cv%20%3D%2017.32m%2Fs)
Therefore, the speed of the brick dropped by the builder as it hits the ground is 17.32m/s.
Learn more about equations of motion: brainly.com/question/18486505
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